Formatting the card will delete all the data on it. Buy a new card for use now, then use data recovery software on your computer to try to salvage the contents of the original card.
This camera is ancient by today's standards, at least 8 years old.
Your focus problem is that the back display is very low resolution, so it will never show a sharp image. 9MP should give a decent image when you view it on a computer. If not, you probably need to part with the camera. it is not worth much these days anyway.
Taking it apart and cleaning it is not going to fix this. White rice may remove excess moisture, but does nothing for the salt. You can't clean corrosion that has already begun. As the camera is not currently working, the damage has already been done.
The reason is that the images were not created on the camera in question. Each camera model saves pictures on a card in a proprietary naming protocol, and if your images do not adhere to this, they cannot be recognised by the camera
There is no built in speaker in Polaroid iS426 camera. You can play your videos when imports on your PC. So don't worry about that. Thanks Fazal Zahoor Bangash from Pakistan
Two possible solutions.
1. Apple users have reported that the switch on the memory cards performs the file lock function in either extreme positions Lock/Unlock. In some cases they have achieved success in centering the Lock/Unlock switch allowing access to the read/write operation of the memory card
2. Connect to PC
Access drive via windows explorer
Right click on drive (MEMORY CARD)
Select properties
Confirm that RO (Read Only) is not selected.
Selected RO
Try reading card
Repeat properties un-select RO
Try deleting files
If not successful card is likely defective
Hope this helps?